ALMOST every one has at some time wondered whether there is any truth in phrenology. The figures of heads, on which various mental faculties are marked, are to be seen everywhere, and the notion that from the shape of the head the character can be determined has enough of the mysterious in it to prove attractive. The thought that some one may discover our little foibles and more serious deficiencies—for it is these rather than our strong points that we are afraid of having found out—makes the study of bumps disagreeably interesting. And perhaps the desire to find out a little more about our friends than they would wish us to know adds somewhat to its attraction.

It is pretty well agreed among scientists, at present, that the old system of phrenology has no actual basis of fact, and that elections upon the skull do not indicate masses of brain beneath them. But to this old system of Gall modern science really owes a great deal; for, like every false idea, it had within it a little kernel of truth, and the interest excited by the claims of its supporters awakened a discussion which has led to a discovery of the greatest importance in the saving of human life.

The claims of Gall that each part of the brain presided over some mental faculty stimulated Flourens, the leading French physiologist of forty years ago, to a series of experiments which seemed to show the falsity of Gall's hypothesis. These experiments in turn were disputed and led to others, and thus interest in the brain and its action was stimulated, until in 1870 the subject was taken up in Germany, and facts were discovered which form the basis of our present knowledge of brain action.

For in Germany a method of testing the action of the brain was invented by Fritsch and Hitzig in 1870. These men noticed that when they applied an electric shock to the brain of an anæsthetized dog, the result was a movement of the limbs. To cause this movement a certain part of the brain had to be irritated by the electricity, other parts being irresponsive; and it was even possible to distinguish the part which moved the fore-leg from that which moved the hind-leg, while, queerly enough, the irritation of one side of the brain always caused movements in the other side of the body. This was an important discovery, for it showed that one part of the brain governed motions while the other parts had nothing to do with motion.

The German investigators went a step further. They said, "If this part of the brain really governs motion, then when it is removed the dog will lose the power of movement," and this reasoning was found in fact to be correct; for when this part, which they named "the motor area," was taken away, the animal was found to be paralyzed, while removal of other parts had no such effect. These experiments, since that time repeated in every laboratory of Europe and America, and tried upon various animals, have established the fact that there is in the brain a certain part which directs voluntary movements.

The second step toward the new phrenology was taken in England in 1873 by David Ferrier. Reasoning from the fact that our movements are usually the result of some preceding sensation, he concluded that sensation as well as motion must be governed by the brain. If motion is governed by one part, sensation may be received in another part. This reasoning led him to undertake a series of experiments to settle the question. He soon succeeded in showing that sensations, which are received by the various sense organs of our bodies—by the eye, ear, nose, mouth, or by the skin—are all sent inward to the brain, and that each of these organs sends its impressions to a distinct region of the brain; sensations of light going in one direction, those of sound in another, and so forth.

The work of Munk, of Berlin, in 1881, confirmed and added to the discoveries of Ferrier, and finally established the conclusion that sensations as well as motion can be located. So that to-day it is possible to lay out a sort of map on the brain of animals, and to say that each of the regions put down on the map has a particular sense with which it is related. On such a map there are here and there empty spaces, such as there are on our geographical maps of Africa—for no one knows what is there. But that, of course, does not invalidate our knowledge of regions which are known, and only shows that further discovery is possible. When we come to see the practical results of these discoveries, the arguments of those who oppose vivisection will cease to interest or move us.

These physiological experiments, however, are only of importance to us in our study of our own mental action, provided they have a bearing upon the working of the brain in man. And this is a question which has only been settled within the past fifteen years. It was admitted, indeed, that in the structure and appearance of his brain man resembled quite closely the higher types of gorilla and ape, and yet the apparently impassable barrier between men and animals as regards mental activity prevented any hasty conclusion that these facts could be applied to men. The question whether sensation and motion could be assigned to parts of the brain in the human race was still (ten years ago) an open one. Of course, it is impossible to experiment upon the human brain. But on a little consideration it soon became evident that Nature was really furnishing the observer with a series of natural experiments on man in the form of disease. The physiologist removed a piece of the brain and watched the loss of sight or hearing, or the loss of motion which ensued. The physician, on the other hand, watches the same kind of loss of sight and hearing, or of motion, in his patient, and may perhaps conclude that here too a loss of brain-tissue is the cause. And this conclusion was confirmed by further observation. Perhaps this may be made a little clearer if we add a fact or two regarding the way in which these experiments of nature are conducted. The blood which is sent to the brain at every throb of the heart goes up in a set of tubes, which give off side branches, like the system of water-pipes which connect your basins with the reservoir. Each tube gets smaller as its branches are given off, until at the end, instead of one large pipe, there is an innumerable series of little end pipes, each throw-out its little stream.

Let us picture to ourselves the water-pipe system of a town set up on a frame aboveground, with the great main, the street mains, the house pipes, and the little pipes all over the houses, all in view, and we will have a sort of conception of the brain's vessels and its blood-supply. Now, it is easy to see that, if a stick or a mass of leaves start out from the reservoir into a main, they will go on and on till they reach a pipe too small to allow them to pass, and there they will lodge. If the stick gets into one's house pipe, one's entire house will be cut off from the water-supply; if the mass of leaves breaks up, a few particles may come in and plug up a pipe to one only of the basins. But in either case the basin will be as useless for washing purposes as if there were no reservoir at all. Now, something very similar to this occurs in disease. Little plugs sometimes come up to the brain from the heart in the blood, and lodge in the little vessels which conduct the blood to various parts of the brain; and when the part of the brain is thus cut off from its supply of nutrition, it gradually withers up and ceases to act.

But when it ceases to act, a loss of some one sense results, just as in the dog when a part of the brain was cut out a loss of some sense occurred. When these facts were studied in this way, it soon became evident that in some persons it was the sight, in others the hearing, in others some other sense, in others still the power of movement which was lost; and further study showed that the varying effect depended upon which part of the brain was deprived of nutrition and was withered, just as in the dogs the location of the part removed determined which sensation was destroyed; so that a striking parallel between the results of experiment and the results of disease can be drawn; and thus the conclusion is arrived at that what is true of animals is true of man, that in man as well as in animals certain regions of the brain can be mapped out and can be assigned to the different senses. It has thus been proved that in their action as well as in their structure the brains of man and of animals are alike.

If in structure and in function all brains are somewhat similar, it may be interesting to obtain a little notion of what a brain is really like. The figure will demonstrate this very well.

Fig. 1.—Diagram of the External Surface of the Left Cerebral Hemisphere (modified from Ecker).

It shows that the brain is an egg-shaped organ with an irregular surface of a yellowish-gray color. The irregularities are formed by a folding of the surface layer so as to accommodate itself to the small space in the head. To illustrate this, when a handkerchief is spread out over the hands it takes up a great space, and a box in order to hold it would have to be of large size; but by gathering the handkerchief up in the hands it is thrown into folds, and, although its actual surface is not decreased, the space it occupies is much diminished, and it could now be put in a very small box and yet all be there, but then its surface would be irregular and show many creases. Now, what was done to the handkerchief Nature has done to the brain as it has developed. In the lower animals and in an early stage of life the folds are few and simple, but in man when full grown they are many and complex. This only means that the actual surface of the train if spread out would be much greater in man than in the lower animals, and far too great to be laid out flat within the head. There are many interesting facts which make one believe that the greater the extent of brain surface in a man, or, to put it a little differently, the more the folds and deeper the creases between them, the greater are the man's mental powers; and just here it becomes apparent that to judge of the extent of the entire brain surface by the size of the head, or by the extent of the superficial irregular surface which is covered by the skull without any regard to the number of folds or their depth, is to fall into an absurd error, and here we begin to see how baseless the old phrenology really is.

For a little brain with many deep folds may really when spread out have a larger surface than a large brain with few shallow folds, and a so-called bump or elevation on the apparent surface of the organ, even if it produces a corresponding elevation on the head, which it frequently fails to do, will indicate nothing regarding the number of the folds or the depth of the creases which lie about it, so that it may be stated without hesitation that from the size or shape of the head no conclusion whatever can be made as to the extent of surface of the brain, and consequently no conclusion can be reached regarding the mental capacity.

But what lies underneath the brain surface? The inner structure of the brain is interesting. Everywhere coming off from the under surface are white threads which gather into bands and pass downward and inward, and finally come out below in the form of nerves. These are the lines of communication by which messages from various parts of the body reach the brain, and along which the impulses are sent out from the brain to the body which result in speech and action. Imagine for a moment that from every part of your hand little threads pass up the arm and find their way to the brain, and there go to a special part of its surface and end. It can be seen at once that you would have a little map of the hand laid out on the brain surface, projected there, to use the terms of the geographer; and in fact such a map of the entire body could really be drawn on the brain surface if we could follow all the little threads to their ends. A sensation which has been sent in from your little finger has always gone to a definite place in your brain, and whenever a message passes along that thread and goes to the brain you feel a sensation in the little finger. The thread goes along your funny-bone at the elbow, and if you happen to strike it there you send a message along it to the brain; but as all such messages have usually come from the little finger, the brain supposes that this one has also come from there, and that is the reason that, although you strike your funny-bone, you feel it in the finger. That also is the reason why people whose fingers have been cut off often say that they have pain in the missing finger, and when you are seated on a hard or uncomfortable chair your foot "goes to sleep."

Now, just as the fingers are joined to the brain we must believe that the other organs are joined to it. Thus the eye sends in its thousands of little threads to one part of the brain surface, the ear to another, the nose and tongue to another. So that each of

Fig. 2.—Diagrammatic Representation of the Direction of some of the Fibers in the Cerebrum (Le Bon) The foldings of the surface; the association fibers joining different regions of the surface with each other; and the fibers passing down to the organs of sense are shown.

the organs of sense is related to a special region of the brain. And each of these regions receives messages from its own particular organ and from no other. That is what is meant by the term localization of brain functions; namely, that each power of sensation can be assigned to a location of its own. This idea aids very materially our conception of the senses. The sense of sight, for example, can not be thought of as dependent upon the eye alone, but upon the eye and the visual part of the brain surface with their connecting threads. And, after all, we must admit that we do not really see with our eyes or hear with our ears. Why does your friend want to hurry through an art gallery, while you wish to look carefully at the paintings? You both see them with your eyes alike. Is it not because behind the eye there is something that is mental which enhances your enjoyment, and the lack of which prevents him from appreciating the beauties of art?

Go to a concert, and, as you come away, listen to the comments of people about you. One says that he was occupied chiefly in watching the gyrations of the man who plays the kettle-drums. Another is indulging in raptures over the intricate counterpoint displayed in the orchestration of the symphony. You have enjoyed the music without perhaps having noticed the counterpoint at all. And yet you and the other two have heard equally well, so far as the actual hearing goes. But how differently you have really heard! It has been the reception of the sounds in the brain, rather than in the ear, the appreciation of their meaning, the ideas awakened by the sensations there, which has determined this difference. You see and hear with the brain, and not with the eye or ear.

Or take another function of the brain, that of voluntary movement. You may be fairly skillful and graceful; you may have learned to write a good hand, or to play on the piano; you may even have succeeded in acquiring the power to pronounce foreign languages with the ease and fluency of your own. But this is not the limit to the knowledge of movement. There are many new motions which you might acquire; for example, the steps of new dances, the peculiar fingering of the violin or cornet or other musical instruments, or some one of the innumerable fine adjustments of motion which you see made with such rapidity by any one of fifty different operatives in every factory in the land. All these are movements of adaptation and adjustment, first studied by the aid of sight and then imitated by the aid of muscular sense, or the sense of movement, and finally acquired by practice till they can be executed with dexterity. It is not the fingers or the muscles which have learned the movements. It is the brain which, in its motor area, has received the sensation of movement, has retained a memory, and then combined the memories into new forms of motion so as to direct and guide the hand which carries them out. And so, though we all have hands and arms, there are some who use them deftly and are skillful, and there are others who will always be hopelessly clumsy and awkward. And the difference lies in the brain in the part called the motor area.

Where are the various areas? They can be shown by the aid of diagrams representing the brain surface (Figs. 3 and 4). In the middle lies the motor area (Fig. 3, 1), and it is interesting to know that on the left half of the brain, which guides the right hand, it is larger in extent than on the other side which controls the left hand; because the majority of fine movements are performed by the right hand, and have to be learned by the left brain. The reverse is true of left-handed people.

At the extreme back is the visual area which receives impressions from the eye (Fig. 3, 2; Fig. 4, 2). In the lower part Fig. 3.—The Functional Areas on the Brain Surface. The parallel lines show the situation of different areas: 1, area of motion; 2, area of sight; 3, area of hearing; 4, area of smell and taste; 5, area of touch. of the side the auditory area is situated, where impressions from the ear are received (Fig. 3, 3). On the under surface and in front of the auditory, the senses of taste and smell are located (Figs. 3 and 4, 4). Touch, which includes the senses of location and of movement, as well as those of temperature and pain, is assigned to the same area as that of motion, but extends a little farther back (Figs. 3 and 4, 5), and this overlapping of the two is not strange when we consider that our motions are guided by touch; think how differently you lift a heavy lamp or a fine bit of cotton-wool, and you will see how your grasp is guided by touch. These Fig. 4.—The Median Surface of the Right Half of the Brain, showing Functional Areas. are the areas which are thus far discovered, but our knowledge of the brain is by no means complete, for there are large regions, on this African map, of undiscovered country. Fortunately, several Stanleys are on the way.

Let us now, accepting this theory of the localization or functions in the brain, go on to see how much it reveals to us regarding the process of thinking.

Although a part of our thinking is done by the aid of language, the greater part of it is carried on without the consciousness of actual words. Mental images are constantly passing through the mind, one crowding upon another; and it is only when we need to tell some one else about them that we use language. Call up to your mind for a moment the place in which you passed last summer, and already there has appeared a series of mental images of place and people, of scenes and events, each following the other with amazing rapidity but in silent succession. Max Müller would have us believe that thought without words is impossible, and he even attempts to trace the development of thought by studying the growth of language.[1] But many authorities, scientific and philosophical, teach the contrary, and rather than accept his position one is tempted to undermine it by advancing the opinion that few men think as the student of words does.

If we think, then, by means of mental images largely, it may be worth while to study the structure of a mental image.

When you examine a flower you perceive its graceful shape and form, its exquisite color, its delicate fragrance, and its soft, velvety feel. You say it is called a rose, but—

"What's in a name? That which we call a rose,
By any other name would smell as sweet."

So that without its name you have a mental image of it, which is made up of several distinct sensations. These are the sensations of the rose as it appears to the eye—the visual image; the sensation as it reaches the nose—the olfactory image; and the sensation of its touch, its shape, and softness—the tactile image. These impressions on the different senses have been sent to distinct and separate regions of the brain surface. There, having been received, they are stored up, so that the image once formed can be recognized when repeated and can be revived in memory.

Every sensation leaves behind it a trace upon the brain, which trace is the physical basis of our memory of the sensation. Perhaps no modern conception of the physical basis of memory is more graphic than that which we find in Plato. In the "Theætetus" he puts the following words into the mouth of Socrates:

"I would have you imagine, then, that there exists in the mind of man a block of wax, which is of different sizes in different men, harder, moister, and having more or less purity in one than in another. Let us say that this tablet is a gift of Memory, the mother of the Muses, and that when we wish to remember anything which we have seen or heard or thought in our own minds, we hold the wax to the perceptions and thoughts, and in that receive the impressions of them as from the seal of a ring; and that we remember and know what is imprinted as long as the image lasts; but when the image is effaced or can not be taken then we forget and do not know."[2]

Plato carries out the same figure to explain different degrees of memory. When the wax is deep, abundant, smooth, and of the right quality, the impressions are lasting. Such minds learn easily, retain easily, and are not liable to confusion. But, on the other hand, when the wax is very soft, one learns easily but forgets as easily; if the wax is hard, one learns with difficulty, but what is learned is retained.[3]

In some way or other, we do not know exactly how, the sensations leave behind them impressions or memory pictures. And these separate memory pictures are associated together, as they have all come from the same object; so that, the association Fig. 5.—Diagram to illustrate the Concept Rose.
Each memory is the relic of a past perception, acquired through an organ of sense. These memories are associated, forming together the concept.
The lines from the rose represent the channels of sensation; the lines between the circles the association tracks. The mouth and hand are the motor organs of speech and writing. being once made, any one will bring to mind the others, and hence if you perceive the fragrance you remember the appearance of the flower from which it comes—its color or its feel. This association of separate memory-pictures is secured by means of fine nerve-threads, which pass between the various areas of the brain and join the parts of the mental image with each other. This may be represented in the diagram (Fig. 5) by placing a circle for each memory-picture in its appropriate place and joining the circles by lines. The circles represent those little round masses of brain substance called nerve-cells, and the lines the association nerve-fibers uniting the cells (Fig. 6). The diagram shows the physical basis of the mental image of a rose—what has been called by Romanes a "recept," since its elements have been received by the senses.[4] What is true of the rose is true of every other object which we have ever learned to know, for of every object we have a recept, or a series of mental images in the brain.

We are constantly increasing our store of mental images, and when one contrasts the small number of such images in the brain of a common uneducated day-laborer with the myriads in the brain of one who has traveled widely, has become familiar with Fig. 6.—The Location of the Memory-Pictures in the Mental Image of a Rose on the Brain Surface. The different memory-pictures are joined by association fibers. the stores of information in foreign languages as well as in his own, and has cultivated his powers of observation in many different directions—for example, such a great leader of thought as Gladstone—one can not but be amazed at the capacity of work in this little organ, the brain. And if there is a physical basis for each of these mental images, is it not evident that in the brain of a Gladstone large areas must be taken up which in the laboring man are really empty? We have seen that on our brain-map there are some empty spaces. There is every reason to believe that these grow smaller as our information widens; and, if so, then, like the undiscovered country of Africa, they should really be a stimulus to efforts of further conquest.

But this mental image of the rose, as represented in the figure, is not really a complete image until it is associated with a name. And the mental image of the name is not as simple as might at first be supposed; for you have not only learned to recognize the word "rose" when you hear it, or when you see it printed, but you have also learned to say the word and to write it, so that you really have a word-image "rose" made up of two sensory images, auditory and visual, and of two motor images, or the memory of the effort necessary to use the word in speech and in script. It is necessary to add then four more circles to the diagram to show the physical basis of the word "rose," and each of these must be placed in its own special region, which has been determined by a long series of investigations. These circles, too, must be joined together, since all the parts of the word are connected in the mind; and, finally, the word-image and the mental image, in all their parts, must also be associated (Fig. 7). Thus the complete mental image of such a simple object as a rose is made up of numerous distinct mental pictures, each joined to all the others, and each located in its own particular domicile. Now, such a mental image is termed a concept, and concepts are the material of thought. Thought is the play of consciousness among these concepts—a play which always, in our waking hours, is within definite boundaries and along lines of association. The oddity of our dreams arises from Fig. 7.—The location of the Memory-Pictures of the Word-Image Rose. 1, word-hearing; 2, word-seeing; 3, word-uttering; 4, word-writing memory-picture. the disregard of these lines and boundaries in a semi-conscious state. Many of the concepts are related to one another. Thus the rose is only one of many flowers which you know, and the term "flower" really brings to a focus all the images of the different roses, chrysanthemums, pansies, and pinks and varied objects which the most complete horticultural exhibition can display. The term "flower"—which we may call an abstract term, because it stands, not for a single object, but for a class of different objects with common features—enables us to handle these many mental images easily and communicate the pictures before our minds to others. It is a convenience, then, to use the word; but, nevertheless, it is the mental images, rather than the words, which play the greater part in our thinking.

This has been most ably expressed by the Duke of Argyll, who says: "Images are repetitions of sensation, endowed with all its mental wealth, and consciously reproduced from the stores of memory. Without images we can do nothing in the fields of thought, while with images we can mentally do all things which it is given us to do. The very highest and most abstract concepts are seen and handled by our intellects in the form of voiceless imagery. How many are the concepts roused in us by the forms and by the remembered images of the human countenance! Love and goodness, purity and truth, benevolence and devotion, firmness and justice, authority and command—these are a few, and a few only, of the abstract ideas which may be presented and represented to us in every degree and in every combination by the remembered image of some silent face. What a wealth of concepts is set before us, for example, in the images raised by this single line:

'Her eyes are homes of silent prayer'!

"Introspection will convince us—perhaps to our own astonishment—how large a part of our thinking operations are conducted through the raising and recalling of remembered images."[5]

But it may be objected that one can not spend one's time in day-dreams, or in the mere pleasures of memory and imagination. You say that reason and action are the real things of life. Have these, too, such a physical as well as a mental basis? Let us follow one or two simple acts of reasoning for a moment. When you see a rose, although it is at a distance from you, you will admit that you believe it to have a fragrance. You conclude that it has, because in your former experience with roses you remember that, when you have held one near, you have always perceived its perfume. The association of the sight of the rose and the fragrance has become fixed in your mind, and when you see it your thought is led along to its fragrance, and you draw the conclusion that the rose is fragrant. That is an act of reasoning. Supposing some one says that the rose sounds sweetly. You have no association between such things as roses and sounds in nature, and your thought refuses to run along where there is no track. You reply that he is talking nonsense—that is, the unreasonable.

Or take another example. Your dog sees you go into the hall and take up your hat and cane; he at once jumps up and runs about, showing by his action that he has come to the conclusion that you are off for a walk, and that he wants to go with you. What is the basis of this process of reasoning? He has a mental image of this act of yours, associated with another mental image of a run on the lawn, and the first calls up to his mind the second. In his experience one act has usually followed the other, and he draws the conclusion that you are going out where he can run. You say at once that the dog has reasoned correctly. It may even be true that the dog has learned to understand language. Many dogs know the word "out," and it calls up to them as distinct a mental image as your act of putting on your hat. Sir John Lubbock has even taught his dog to read;[6] for, by showing him a large card on which the word "water" was printed, every time he gave him a drink, an association was established in the dog's mind between the card and the act; and, finally, when the dog wanted a drink, he would bring the card in his mouth to his master. Ten such different words were taught him, and he rarely made a mistake. So that the understanding of speech and of writing and the act of reasoning, so far as simple conclusions go, from the recollection of mental images, may be granted to animals as well as to man. And these acts of reasoning, like those of memory, have as a basis the association of ideas. It may be admitted at once that many high processes of thought involve the following of association along many lines at once, or in such a complex way that to picture them clearly to the mind would be an almost impossible task. But there appears to be no essential difference in kind between the simple conclusions which have been used as illustrations and the more complex ones involved in abstract reasoning. The logician will reduce all your acts of reasoning to certain syllogisms which it is now quite customary to express in algebraic formulæ. For each of these formulæ it is possible to picture a physical basis of nerve-cells, joined together by nerve-fibers, so that it seems probable that the mechanism of thought will some day be understood. Our thoughts are usually so rapid and so many that we do not stop to analyze them, but, when we do, we find them always the result of a gradual accretion of ideas and not a new creation. The inventor will tell you that his most brilliant discovery did not spring suddenly into his mind in all its perfection, but was gradually led up to, step by step, with many halts and puzzling alternatives. Finally, old mechanisms and principles, formerly familiar, were successfully associated together with new adaptations into a new unit, and the ingenious mechanism was complete. The evolution of the locomotive, of the telegraph, and of the telephone teaches us the process in the inventor's mind as clearly as it shows his genius for construction. There are many other mental processes which might be followed out which display equally well how closely reasoning depends on the association of ideas—i.e., upon the play of consciousness along lines of communication between different regions of the brain. But we must pass on to some illustrations of action.

Watch a game of tennis and notice the difference between players, and you can tell a great deal about their mental processes. One is quick to see the ball, to note its direction, and to calculate its speed and the position it will reach in a moment, and yet from a lack of quickness in movement or from clumsiness he is unable to return it well. Another is particularly agile and graceful, plays all over the field, and seems to be everywhere at the right time; and you think him the better player. But as you watch you find that he judges the ball badly, and is not accurate in his calculation as to where it is going or when it will fall. The champion player is the one who combines accuracy and quickness with precision and agility. The sight of the direction of the ball leads him at once to a correct judgment of how far he has to run or reach for it, and his movement is quick enough and directed with just sufficient force to make the return. Now, this matter of precision of movement is dependent upon a process of perception, association, and effort, and is to a great extent a matter of inborn capacity. The physicists express this by saying that each of us has his personal equation. Perhaps this will be more easily understood if we follow the manner in which it was discovered. One of the interesting astronomical events is the eclipse of Jupiter's moons as they pass behind the planet and disappear from the astronomer's view. Maskelyne, British astronomer royal, and his assistant in the Greenwich Observatory, in 1795, sitting side by side and looking through two telescopes, were attempting to record very accurately the moment at which the eclipse was complete. It was found that their records differed from one another by some fractions of a second. And the differences were about the same when other observations with a similar object were made. The explanation of these differences has been found, after many years of investigation, to be due to a difference in the rapidity with which each man observed and recorded his observation, and those differences can now be measured. This was not appreciated at first, for we find that the result of this discovery of a difference between the records of the two observers was very unfortunate to one of them; for in his annual report Maskelyne writes:

"I think it necessary to mention that my assistant, Mr. David Kinnebrook, who had observed the transits of stars and planets very well in agreement with me all the year 1794, and for the great part of the present year, began from the beginning of August last to set them down half a second of time later than he should do according to my observations; and in January of the succeeding year, 1796, he increased his error to eight tenths of a second. As he had unfortunately continued a considerable time in this error before I noticed it, and did not seem to me likely ever to get over it and return to the right method of observing, therefore, though with reluctance, as he was a diligent and useful assistant to me in other respects, I parted with him."

Thus Mr. David Kinnebrook fell a victim to the earliest discovery of the difference of power of observation.

How these differences were measured it would take too long to relate. The results only can be stated, and for details reference made to an article by Prof. Cattell in a recent number of "The Popular Science Monthly" on "The Time it takes to Think," and to one by Prof. Sandford, in the "American Journal of Psychology," on the "Personal Equation."[7]

Any act which depends upon sensation, such as returning a tennis-ball or replying to a question, takes time. This act can be separated into certain parts. There is the perception of the sensation, the decision to respond to it, and the act of motion. You hear the question, you think of the answer, and you say it. Each of them has been separately measured, and takes from one tenth to one sixth of a second, so that the entire process requires from three tenths to one half of a second to complete it. People differ widely from one another in this rapidity of action, and the same person differs much at different times, and the explanation of this difference is found in the inherent power of activity in the brain. The effect of wine is to make these acts slower. The action as a whole calls into activity several parts of the brain, the nerve from the organ of sense to the brain, the part receiving the sensation, the tract from it to the motor area, and the part of that area which initiates the impulse and guides the movement and the nerve thence to the muscles. It is not surprising, therefore, that it should take some time; the astonishing thing is really the rapidity with which the brain acts, for modern measurements extend to thousandths of a second, and some mental processes in rapid brains take only a few hundredths of a second to be completed. Familiarity with a certain act lessens the time it requires. A lady was heard to say the other day, in alluding to the acting of the French comedians who have recently been seen here, that it was surprising how much faster French people talked than Americans. She would have thought it an act lacking in courtesy had it been insisted upon that it was not because they really talked faster, but because her English-speaking brain refused to think as rapidly in French, that had led her to the conclusion. Yet such was the fact.

There is one more process of mental activity to which allusion must be made, as it has thrown much light upon the theory of localization, and has now been fully explained by that theory—viz., the power of speech. There is perhaps no mental process which brings us more closely to the point of meeting of the physical and mental elements of the mind.

Language is so complex, as we survey it and as we constantly use it, that it seems at first impossible to unravel all its mysteries. But, if we watch its growth, we can get at some facts of not a little interest. Let us trace the way in which a baby learns its first word.[8] As the baby looks about him he begins after a time to distinguish faces, and one face, his mother's, being constantly near, soon becomes most familiar. Mothers are constantly talking to their babies, and always speak of themselves as "mamma" or "mother," never using "I" or "me." After a time the baby begins to notice this sound "mamma" and to recognize it, and then the fact that a certain face and a certain sound usually come together finally establishes a fixed association between the sight-picture and the sound-picture, so that the one when brought to mind brings up the other. Then, if you ask the baby, "Where is mamma?" He will look about the room until he finds the familiar face. He has now taken his first step in acquiring speech, he has learned the meaning of a word. The second step follows after a time. From time immemorial in the baby's experience he has been able to cry, and he knows it; in other words, he is aware of the fact that it is one of his native powers to make a noise. By and by it begins to occur to him that this sound, "mamma," is also a noise, and some day, probably by accident, as he is being cruelly shaken up by being trotted on some one's knee, he emits a sound like "mamma." If he is a bright baby—and whose baby is not?—he notices the similarity between the sound he has made and the sound he has already learned. Such attempts at saying "mamma" usually meet with considerable active encouragement of an agreeable kind, and he naturally repeats the attempt. After many failures it is a success, and he has at last acquired a memory of the exact effort in certain muscles of lips and tongue needed to produce the sound, and has also associated that memory of effort with the memory of the sound which in time is joined to the memory of the mother's face. And now the second process is complete, and the baby knows how to say the word intelligently; for intelligent speech is speech based upon an association of ideas. Of course, as the child grows, he subsequently adds a visual picture of the word "mamma" to the auditory picture when he learns to read; and a manual-effort memory to the speech-effort memory when he learns to write. When all these four memories are acquired and associated, he has acquired the use of language.

Now, what is true of this simple word has been true of every other word which we make use of; and, though we can not recall this process which we have been through, we can see it going on about us. If you wish to study it carefully, study children, by the aid of Preyer's interesting book, "The Mind of the Child."[9] Or if you wish to observe the process more directly, recall the manner in which you have acquired a foreign language, for that is done in the same way, if the natural method is followed. Suppose that you are told that in German the brain is called Gehirn—that it is pronounced gayheern, and spelled g-e-h-i-r-n. If you are not familiar with German, you have now a new word-image connected with the mental image of the brain much more easily acquired than was the word "mamma" when you learned it, but nevertheless acquired in the same way.

Whether we think, then, in mental images or in language, the process is the same; it is consciousness playing along certain lines of association to and fro between definite memory-pictures. These memory-pictures have been acquired through the senses, each through its own particular channel of sensation, and are stored up in the brain, each in its particular part of the brain.

Memory is the revival in consciousness of these various memory-pictures.

Imagination is the combination of old pictures into a new image.

Reasoning is the passage of thought from one picture to another, along established lines.

Action is the carrying out of the impulse to whose memory reason has led up.

These are some of the mental faculties, and it is at once evident that they are not distinct entities, like the mental image, but rather powers of the mind to deal with these images; and, therefore, the faculties can not be said to have any particular seat, and can never be located in an area of the brain. Imagination and reasoning power are therefore not to be assigned to bumps on the head, as the old phrenology taught. And even when we speak of memory we distinguish it broadly from the memory-pictures, which do have a location, but one that is wholly different from that taught by Gall. Here, again, we see how far removed from the old phrenology the new phrenology is, and how much more exact in its knowledge. If proofs of these facts are demanded, they are to be found in the study of diseases of memory, as described in Ribot's entertaining little volume. But one or two statements may be made, very briefly, in closing, which must carry conviction to the most skeptical mind.

The reason why it is now accepted that each sense with its memory-pictures has a definite location in the brain distinct from all others, is that it is possible for one sense or one set of memory-pictures to be lost without affecting the others. There are men in apparently perfect health who have suddenly lost all their sight-memory, so that they no longer recognize people or things formerly familiar. One such man did not even know his wife until she spoke to him, when he at once knew her voice. There are men who have in the course of a few moments been deprived of their memory of language, and who, although they could talk and even write, were as incapable of understanding what was said to them or of understanding what they saw on a printed page as one would be of spoken or written Chinese. There are others still who have lost their artistic or musical powers, but in other respects are perfectly sound, so that instead of being able to sketch from memory as formerly they are unable to call up to mind a single memory-picture; and instead of being able to follow or recollect a melody or appreciate the harmonies of music, they are totally deprived of this pleasure, and this without any blindness or deafness excepting of the mind.

Others, again, lose the power of speech or of writing without having their understanding of language interfered with or without any paralysis of the muscles—the effort-memory of speech is lost.

Such effects find their only possible explanation in the fact that each set of memory-pictures may be destroyed simply, and this is only possible provided they are situated in separate regions of the brain.

And there is a great practical application of all this theory of localization, which has only been reached within the past three years.

If it is possible to locate a set of memories, and in the progress of disease those memories are lost, it is evident that the location of the disease has been determined. Sometimes that disease is of a kind which can be removed—for example, a brain tumor. From a study of such facts as those presented here it has been possible to determine the location of tumors in the brain, and, although externally there was no sign of disease, it has been possible for surgeons to go through the skull to find the tumor and to remove it. Up to the present time about seventy such operations have been done in this country and in Europe, and of these fifty have been successful, and what was formerly considered a necessarily fatal disease has thus been cured.

The practical demonstration of the truth of the new phrenology is therefore complete.

The old phrenology, as we have seen, was wrong in its theory, wrong in its facts, wrong in its interpretation of mental processes, and never led to the slightest practical result. The new phrenology is scientific in its methods, in its observations, and in its analysis, and is convincing in its conclusions. And who can now set a limit to the benefit it has brought to mankind by its practical application to the saving of human lives?